import os
import re
import sqlite3
import tempfile
import threading
import unittest
from contextlib import contextmanager
from pathlib import Path
from unittest import mock

from django.core.exceptions import ImproperlyConfigured
from django.db import (
    DEFAULT_DB_ALIAS,
    NotSupportedError,
    connection,
    connections,
    transaction,
)
from django.db.models import Aggregate, Avg, StdDev, Sum, Variance
from django.db.utils import ConnectionHandler
from django.test import SimpleTestCase, TestCase, TransactionTestCase, override_settings
from django.test.utils import CaptureQueriesContext, isolate_apps

from ..models import Item, Object, Square


@unittest.skipUnless(connection.vendor == "sqlite", "SQLite tests")
class Tests(TestCase):
    longMessage = True

    def test_aggregation(self):
        """Raise NotSupportedError when aggregating on date/time fields."""
        for aggregate in (Sum, Avg, Variance, StdDev):
            with self.assertRaises(NotSupportedError):
                Item.objects.aggregate(aggregate("time"))
            with self.assertRaises(NotSupportedError):
                Item.objects.aggregate(aggregate("date"))
            with self.assertRaises(NotSupportedError):
                Item.objects.aggregate(aggregate("last_modified"))
            with self.assertRaises(NotSupportedError):
                Item.objects.aggregate(
                    **{
                        "complex": aggregate("last_modified")
                        + aggregate("last_modified")
                    }
                )

    def test_distinct_aggregation(self):
        class DistinctAggregate(Aggregate):
            allow_distinct = True

        aggregate = DistinctAggregate("first", "second", distinct=True)
        msg = (
            "SQLite doesn't support DISTINCT on aggregate functions accepting "
            "multiple arguments."
        )
        with self.assertRaisesMessage(NotSupportedError, msg):
            connection.ops.check_expression_support(aggregate)

    def test_distinct_aggregation_multiple_args_no_distinct(self):
        # Aggregate functions accept multiple arguments when DISTINCT isn't
        # used, e.g. GROUP_CONCAT().
        class DistinctAggregate(Aggregate):
            allow_distinct = True

        aggregate = DistinctAggregate("first", "second", distinct=False)
        connection.ops.check_expression_support(aggregate)

    def test_memory_db_test_name(self):
        """A named in-memory db should be allowed where supported."""
        from django.db.backends.sqlite3.base import DatabaseWrapper

        settings_dict = {
            "TEST": {
                "NAME": "file:memorydb_test?mode=memory&cache=shared",
            }
        }
        creation = DatabaseWrapper(settings_dict).creation
        self.assertEqual(
            creation._get_test_db_name(),
            creation.connection.settings_dict["TEST"]["NAME"],
        )

    def test_regexp_function(self):
        tests = (
            ("test", r"[0-9]+", False),
            ("test", r"[a-z]+", True),
            ("test", None, None),
            (None, r"[a-z]+", None),
            (None, None, None),
        )
        for string, pattern, expected in tests:
            with self.subTest((string, pattern)):
                with connection.cursor() as cursor:
                    cursor.execute("SELECT %s REGEXP %s", [string, pattern])
                    value = cursor.fetchone()[0]
                value = bool(value) if value in {0, 1} else value
                self.assertIs(value, expected)

    def test_pathlib_name(self):
        with tempfile.TemporaryDirectory() as tmp:
            settings_dict = {
                "default": {
                    "ENGINE": "django.db.backends.sqlite3",
                    "NAME": Path(tmp) / "test.db",
                },
            }
            connections = ConnectionHandler(settings_dict)
            connections["default"].ensure_connection()
            connections["default"].close()
            self.assertTrue(os.path.isfile(os.path.join(tmp, "test.db")))

    @mock.patch.object(connection, "get_database_version", return_value=(3, 36))
    def test_check_database_version_supported(self, mocked_get_database_version):
        msg = "SQLite 3.37 or later is required (found 3.36)."
        with self.assertRaisesMessage(NotSupportedError, msg):
            connection.check_database_version_supported()
        self.assertTrue(mocked_get_database_version.called)

    def test_init_command(self):
        settings_dict = {
            "default": {
                "ENGINE": "django.db.backends.sqlite3",
                "NAME": ":memory:",
                "OPTIONS": {
                    "init_command": "PRAGMA synchronous=3; PRAGMA cache_size=2000;",
                },
            }
        }
        connections = ConnectionHandler(settings_dict)
        connections["default"].ensure_connection()
        try:
            with connections["default"].cursor() as cursor:
                cursor.execute("PRAGMA synchronous")
                value = cursor.fetchone()[0]
                self.assertEqual(value, 3)
                cursor.execute("PRAGMA cache_size")
                value = cursor.fetchone()[0]
                self.assertEqual(value, 2000)
        finally:
            connections["default"]._close()


@unittest.skipUnless(connection.vendor == "sqlite", "SQLite tests")
@isolate_apps("backends")
class SchemaTests(TransactionTestCase):
    available_apps = ["backends"]

    def test_autoincrement(self):
        """
        auto_increment fields are created with the AUTOINCREMENT keyword
        in order to be monotonically increasing (#10164).
        """
        with connection.schema_editor(collect_sql=True) as editor:
            editor.create_model(Square)
            statements = editor.collected_sql
        match = re.search('"id" ([^,]+),', statements[0])
        self.assertIsNotNone(match)
        self.assertEqual(
            "integer NOT NULL PRIMARY KEY AUTOINCREMENT",
            match[1],
            "Wrong SQL used to create an auto-increment column on SQLite",
        )

    def test_disable_constraint_checking_failure_disallowed(self):
        """
        SQLite schema editor is not usable within an outer transaction if
        foreign key constraint checks are not disabled beforehand.
        """
        msg = (
            "SQLite schema editor cannot be used while foreign key "
            "constraint checks are enabled. Make sure to disable them "
            "before entering a transaction.atomic() context because "
            "SQLite does not support disabling them in the middle of "
            "a multi-statement transaction."
        )
        with self.assertRaisesMessage(NotSupportedError, msg):
            with transaction.atomic(), connection.schema_editor(atomic=True):
                pass

    def test_constraint_checks_disabled_atomic_allowed(self):
        """
        SQLite schema editor is usable within an outer transaction as long as
        foreign key constraints checks are disabled beforehand.
        """

        def constraint_checks_enabled():
            with connection.cursor() as cursor:
                return bool(cursor.execute("PRAGMA foreign_keys").fetchone()[0])

        with connection.constraint_checks_disabled(), transaction.atomic():
            with connection.schema_editor(atomic=True):
                self.assertFalse(constraint_checks_enabled())
            self.assertFalse(constraint_checks_enabled())
        self.assertTrue(constraint_checks_enabled())


@unittest.skipUnless(connection.vendor == "sqlite", "Test only for SQLite")
@override_settings(DEBUG=True)
class LastExecutedQueryTest(TestCase):
    def test_no_interpolation(self):
        # This shouldn't raise an exception (#17158)
        query = "SELECT strftime('%Y', 'now');"
        with connection.cursor() as cursor:
            cursor.execute(query)
        self.assertEqual(connection.queries[-1]["sql"], query)

    def test_parameter_quoting(self):
        # The implementation of last_executed_queries isn't optimal. It's
        # worth testing that parameters are quoted (#14091).
        query = "SELECT %s"
        params = ["\"'\\"]
        with connection.cursor() as cursor:
            cursor.execute(query, params)
        # Note that the single quote is repeated
        substituted = "SELECT '\"''\\'"
        self.assertEqual(connection.queries[-1]["sql"], substituted)

    def test_parameter_count_exceeds_variable_or_column_limit(self):
        sql = "SELECT MAX(%s)" % ", ".join(["%s"] * 1001)
        params = list(range(1001))
        for label, limit, current_limit in [
            (
                "variable",
                sqlite3.SQLITE_LIMIT_VARIABLE_NUMBER,
                connection.features.max_query_params,
            ),
            (
                "column",
                sqlite3.SQLITE_LIMIT_COLUMN,
                connection.connection.getlimit(sqlite3.SQLITE_LIMIT_COLUMN),
            ),
        ]:
            with self.subTest(limit=label):
                connection.connection.setlimit(limit, 1000)
                self.addCleanup(connection.connection.setlimit, limit, current_limit)
                with connection.cursor() as cursor:
                    # This should not raise an exception.
                    cursor.db.ops.last_executed_query(cursor.cursor, sql, params)
                connection.connection.setlimit(limit, current_limit)


@unittest.skipUnless(connection.vendor == "sqlite", "SQLite tests")
class EscapingChecks(TestCase):
    """
    All tests in this test case are also run with settings.DEBUG=True in
    EscapingChecksDebug test case, to also test CursorDebugWrapper.
    """

    def test_parameter_escaping(self):
        # '%s' escaping support for sqlite3 (#13648).
        with connection.cursor() as cursor:
            cursor.execute("select strftime('%s', date('now'))")
            response = cursor.fetchall()[0][0]
        # response should be an non-zero integer
        self.assertTrue(int(response))


@unittest.skipUnless(connection.vendor == "sqlite", "SQLite tests")
@override_settings(DEBUG=True)
class EscapingChecksDebug(EscapingChecks):
    pass


@unittest.skipUnless(connection.vendor == "sqlite", "SQLite tests")
class ThreadSharing(TransactionTestCase):
    available_apps = ["backends"]

    def test_database_sharing_in_threads(self):
        thread_connections = []

        def create_object():
            Object.objects.create()
            thread_connections.append(connections[DEFAULT_DB_ALIAS].connection)

        main_connection = connections[DEFAULT_DB_ALIAS].connection
        try:
            create_object()
            thread = threading.Thread(target=create_object)
            thread.start()
            thread.join()
            self.assertEqual(Object.objects.count(), 2)
        finally:
            for conn in thread_connections:
                if conn is not main_connection:
                    conn.close()


@unittest.skipUnless(connection.vendor == "sqlite", "SQLite tests")
class TestTransactionMode(SimpleTestCase):
    databases = {"default"}

    def test_default_transaction_mode(self):
        with CaptureQueriesContext(connection) as captured_queries:
            with transaction.atomic():
                pass

        begin_query, commit_query = captured_queries
        self.assertEqual(begin_query["sql"], "BEGIN")
        self.assertEqual(commit_query["sql"], "COMMIT")

    def test_invalid_transaction_mode(self):
        msg = (
            "settings.DATABASES['default']['OPTIONS']['transaction_mode'] is "
            "improperly configured to 'invalid'. Use one of 'DEFERRED', 'EXCLUSIVE', "
            "'IMMEDIATE', or None."
        )
        with self.change_transaction_mode("invalid") as new_connection:
            with self.assertRaisesMessage(ImproperlyConfigured, msg):
                new_connection.ensure_connection()

    def test_valid_transaction_modes(self):
        valid_transaction_modes = ("deferred", "immediate", "exclusive")
        for transaction_mode in valid_transaction_modes:
            with (
                self.subTest(transaction_mode=transaction_mode),
                self.change_transaction_mode(transaction_mode) as new_connection,
                CaptureQueriesContext(new_connection) as captured_queries,
            ):
                new_connection.set_autocommit(
                    False, force_begin_transaction_with_broken_autocommit=True
                )
                new_connection.commit()
                expected_transaction_mode = transaction_mode.upper()
                begin_sql = captured_queries[0]["sql"]
                self.assertEqual(begin_sql, f"BEGIN {expected_transaction_mode}")

    @contextmanager
    def change_transaction_mode(self, transaction_mode):
        new_connection = connection.copy()
        new_connection.settings_dict["OPTIONS"] = {
            **new_connection.settings_dict["OPTIONS"],
            "transaction_mode": transaction_mode,
        }
        try:
            yield new_connection
        finally:
            new_connection._close()
